1. Field of the Invention
This invention relates to a magnetoresistance effect element formed by using multilayer of ultra-thin layers or a so-called artificial lattice film.
2. Description of the Related Art
The magnetoresistance effect is an effect of varied resistance of an object caused by the variation in the intensity of the magnetic field applied to it. Magnetoresistance effect elements that utilize this effect find a variety of applications including those for magnetic field sensors and magnetic heads because of the high sensitivity to magnetic fields and the ability to produce a relatively large output of such elements. While Permalloy thin film is wide used for magnetoresistance effect elements, the magnetoresistance ratio of a Permalloy foil (.DELTA.R/Rs: where .DELTA.R is the electric resistance change between zero magnetic field and saturated magnetic field; Rs is saturation resistivity) is as low as 2 or 3% and, therefore, does show a satisfactory sensitivity to changes in the magnetic field required for a magnetoresistance effect element.
Meanwhile, as new magnetoresistance effect element, multilayer formed by alternately stacking magnetic and nonmagnetic layers having a thickness of several to tens of Angstroms or so-called artificial lattice films have been attracting attention. Known types of artificial lattice film include (Fe/Cr).sub.n (Phys. Rev. Lett. vol. 61(21) (1988)2472), (Per malloy/Cu/Co/Cu).sub.n (J. Phys. SOC. Jap. vol. 59(9) (1990) 3061) and (Co/Cu).sub.n (J. Mag. Mag. Mat. 94, (1991)L1; Phys. Rev. Lett. 66(1991)2152).
While an artificial lattice film can present a dramatically enhanced magnetoresistance effect when compared with a Permalloy thin film, artificial lattice films having a remarkable magnetoresistance effect can be currently produced only by a film forming apparatus capable of carrying out a supervacuum processing, which uses a supervacuum technique such as the ultra-high vacuum evaporation (UHV) method or the molecular beam epitaxy (MBE) method. Artificial lattice films prepared in an ordinary film forming apparatus do not unfortunately show a satisfactory magnetoresistance effect.